<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #content {
            width: 500px;
            background: red;
            margin: 200px;
        }
        #box  {
            width: 200px;
            height: 200px;
            background: purple;
            padding: 100px;
        }
        #footer {
            width: 500px;
            height: 200px;
            background: blue;
        }
    </style>
</head>
<body>
    <div id="content">
        <div id="box"></div>
    </div>
    <div id="footer"></div>
    <!--
    内容与内填充相同
    -->
</body>
</html>